A long standing problem with wireless communications is the need to maximize spectrum efficiency. Spectrum efficiency refers to the most efficient use of the limited bandwidth that is set aside for a given type of wireless communications. For instance, in the United States, the Federal Communications Commission (FCC) has set aside the portions of the frequency spectrum from 851 to 869 MHz and from 806 to 824 MHz for trunked private two-way radio communications (as used herein, “trunked radio communications”). The first portion of the spectrum is reserved for transmissions by infrastructure in the trunked radio communications system and the second portion of the spectrum is reserved for transmissions by subscribers in the trunked radio communications system. The absolute frequencies of the frequency spectrum are allocated by the FCC and divided into channels by an operator of the infrastructure.
When the FCC changes allocations to the frequency spectrum the mapping between the channels and the absolute frequencies may need to also change to accommodate the changes in allocation. For example, the FCC has changed allocations to the 800 MHz spectrum, where the National Public Safety Planning Advisory Committee (NPSPAC) licensees have all been consolidated to operate in the 806 to 809 MHz spectrum. In such a situation, the time and effort required to perform the mapping between the channels and the absolute frequencies is great. Further, once the mapping is performed, the subscribers need to be informed about the new mapping so that the subscribers can utilize the mapping to use the trunked radio communications system for communications.
Generally, subscribers of the trunked radio communications system are assigned a channel for the subscriber to utilize for a voice call with other subscribers in the trunked radio communications system. Once the subscriber receives its channel assignment, the subscriber must translate the assigned channel to an absolute frequency. When allocations to the frequency spectrum change, the radio may need to perform a new calculation that takes into account the mapping that was performed between channels and absolute frequencies. Further, if the frequency separation between adjacent channels is smaller than previously used, then the subscriber needs to account for the smaller separation when the subscriber utilizes the channel for communications. If the subscriber does not account for the smaller separation, then the subscriber may interfere with communications in adjacent channels.
Thus, there is a need for a new method of operating in an 800 MHz trunked radio communications system for channels 440 to 559.
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